OL 8 must not accept router advertisements on all IPv6 interfaces by default.

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-248885	OL08-00-040262	SV-248885r780221_rule		Medium

Description
Routing protocol daemons are typically used on routers to exchange network topology information with other routers. If this software is used when not required, system network information may be unnecessarily transmitted across the network. An illicit router advertisement message could result in a man-in-the-middle attack.

STIG	Date
Oracle Linux 8 Security Technical Implementation Guide	2021-07-21

Details

Check Text ( C-52319r780219_chk )

Verify OL 8 does not accept router advertisements on all IPv6 interfaces by default, unless the system is a router. Note: If IPv6 is disabled on the system, this requirement is not applicable. Determine if router advertisements are not accepted by using the following command: $ sudo sysctl net.ipv6.conf.default.accept_ra net.ipv6.conf.default.accept_ra = 0 If the "accept_ra" value is not "0" and is not documented with the Information System Security Officer (ISSO) as an operational requirement, this is a finding.

Fix Text (F-52273r780220_fix)
Configure the system to not accept router advertisements on all IPv6 interfaces by default, unless the system is a router, with the following commands: $ sudo sysctl -w net.ipv6.conf.default.accept_ra=0 If "0" is not the system's default value, add or update the following lines in the appropriate file under "/etc/sysctl.d": net.ipv6.conf.default.accept_ra=0